Steam power plant including reheat boiler cycle



Feb. 24, 1959 L. J. cuLvzR' 2,874,543

STEAM POIER PLANT INCLUDING REHEAT BOILER CYCLE Filed Aug. 17, 1954[GOA/OM12 /6 INVENTOR Lem Aka I Cl/L 1/9? United States Patent "iceSTEAM rowan PLANT INCLUDING REHEAT BOILER CYCLE Application August 17,1954, Serial No. 450,289

'3 Claims. (CI. 60-73) The present invention relates to heat exchangesystems and more particularly to a heat exchange system for powergenerators. I

In the usual heat exchange system for power generators, superheatedvapor is produced in a vapor generator after which it is passed to thehigh pressure stage of a turbine for use therein. Thereafter, the vaporfrom this high pressure turbine stage is reheated before his passed tothe low pressure stage of the turbine.

In accordance with the present invention, vapor is produced in a vaporgenerator which is provided with means for controlling the superheatedvapor temperature, and the vapor is thereafter delivered to the highpressure stage of a turbine. The vapor from the high pressure stage isreheated in a vapor generator separate from the main or superheatervapor generator. The reheat vapor generator comprises a setting havingtwo banks of vapor generating tubes which are arranged in series in thepath of flow of the combustion gases and a convection reheater elementis disposed between the tube banks and shielded from radiant heat by thetube bank nearer the furnace. The reheater element is connected toreceive vapor from the high pressure turbine stage and to pass reheatedvapor to the low pressure stage of the turbine. The vapor generatingsurface of the reheat vapor generator is connected to pass variablequantities of saturated vapor to the superheater of the main generatorwithout upsetting the final superheated vapor temperature in the maingenerator.

The invention will be better understood from the following descriptionwhen considered in connection with the accompanying diagrammatic drawingshowing the invention for purposes of illustration as used in a marineinstallation.

Like characters of reference refer to the same parts throughout thedrawing.

Referring to the drawing, the reference character designates the settingof two steam generators each comprising steam generating furnaces 11 and12. The furnace 11 is lined with water wall tubes and fired by burners13 while the furnace 12 is fired by burners 14. A group of steamgenerating tubes 15 extends between an upper steam and water drum 16 anda lower water drum 17 and the tubes are arranged to separate thefurnaces. Tubes 15 are spaced apart from one another to permit gases topass from furnace 11 into the furnace 12. The drum 16 is connected to alower drum 18 by a vertically inclined main bank of steam generatingtubes 19. As shown, a superheater 20 is positioned in the tube bank 19.A saturated steam line 21, extending outside the setting, is connectedto drum 16 and superheater 20 to communicate the drum 16 with thesuperheater. Steam line 21 is in communication with auxiliary steamconsuming equipment (not shown) by an auxiliary steam line 22. Line 22is provided with a-control valve 23. The steam generator illustrated isprovided with a single flue outlet 23' for the gases from both furnaces.The arrangement of the steam generator is such that the gases PatentedFeb. 24, 1959 from'the furnace 11 flow over the tube group 15 into thefurnace 12 and such gases, together with the gases produced in furnace12, pass over the bank of tubes 19 and enter the fiue 23'. Heat recoveryapparatus, such as an economizer 24 and an air heater 24' are disposedin the flue 23'. Steam to be superheated is withdrawn from drum 16through line 21 and delivered to the superheater. t s

The superheater 20 of each vapor generator is connected by a conduit 25to the high pressure stage of a steam turbine 26. An exhaust conduit 27connects the high pressure stage of turbine 26 to a reheat element 28 ofa reheat generator 28, which reheat element 28 may be a conventionaltypeheat exchanger comprising a tubular coil.

Reheat generator 28' comprises a furnace 29 lined with water wall tubesand fired by burners 30. A group of steam generating tubes 31 extendsbetween an upper steam and water drum 32 and a lower water drum 33.Reheat element 28 is disposed in tube bank 31. andis shielded fromradiant heat by the portion of tube bank 31 nearer the furnace. Outletconduits 34 connect reheat element 28 with the low pressure stage inletof each turbine 26. An economizer 35 and an air heater 36 aredisposed ina fiue 37 of the reheat generator. A- saturated steam line 38 isconnected to drum 32 and communicates with the auxiliary steam line 22of each main generator through a connecting pipe 40. Valves 41 areprovided in pipe 40 between line 38 and steam 7 line 22 to control thequantity of saturated steam delivered to each steam line 22.

In operation, gases of combustion produced in each furnace 11, pass inheat exchange relationship with tube banks 15 to cause generation ofsteam which passes into drums 16. Thereafter, the gases of combustionfrom furnaces 11 pass into furnaces 12 to join the combustion gasesproduced in furnaces 12. Gases of combustion, in furnaces 12, pass inheat exchange relationship with tube banks 19 to cause generation ofsteam in the latter, which steam passes into drums 16. The steam fromdrums 16 flows through lines 21 and into superheaters 20 where the steamis superheated by the gases of combustion fiowing thereover. The desiredsuperheat steam temperature is maintained in superheaters 20 bycontrolling the firing of burners 14 in furnaces 12. Superheated steamfrom superheater 20 flows into the high pressure stage of turbine 26through conduit 25 and passes therefrom through the exhaust conduit 27of the turbine into the reheat element 28 of the reheat vapor generatorin the cycle. Gases of combustion in furnace 29 of the reheat boilerpass in heat exchange relationship with reheat element 28 to reheatsteam from the high pressure stage of the turbine. The combustion gasesalso pass over tube bank 31 to generate saturated steam which passesinto drum 32. The reheated steam from reheat element 28 thereafterpasses into the low pressure stage of each turbine 26 through conduits34. The saturated steam from drum 32 passes into the superheater 20 ofeach main boiler through line 38 and connecting pipe 40 thus providingan additional quantity of steam to the system from the reheat boiler.Since separately fired furnaces are provided in each main boiler,positive control of superheat is provided and accordingly the additionalsteam from drum 32 may be passed to the superheaters 20 withoutupsetting the final steam temperature in the main boilers.

If desired, the saturated steam produced in the reheat boiler may beused for auxiliary plant purposes by opening valve 23 in the steam line22 of each main boiler which line communicates with auxiliary equipment,not shown.

Thus, in the present invention when the auxiliary steam 3 v I demand isless than the output of the reheat boiler, the balance of thesaturatedsteam produced in the reheat boiler can be passed through themain boiler superheaters. n the other hand, if the reheat boiler is notproducing enough steam to meet the auxiliary demand then the differencecan be made up from the main boilers and as that difierenc'e will berelatively small, it will not prejudice the output of the main boilersin respect to the demand made on the latter by the steam consumingapparatus, for exaniple, the main engines (not shown) in a marineinstallation.

Inasmuch as various modifications may be made in the embodiment of theinvention herein disclosed without departing from the principlesthereof, it will be understood that the invention is not to be limitedexcepting by the scope of the appended claims.

What is claimed is:

1. In combination, a plurality of vapor generators, at superheater and avapor generating surface disposed in each vapor generator, means forcontrolling the superheated vapor temperature of each vapor generator, aplurality of turbines each having a high pressure'stagc and a lowpressure stage, conduit means in communication with the superheater ofone of said vapor generators and with the high pressure stage of one ofsaid turbines, other conduit means in communication with the superheaterof another of said vapor generators and the high pressure stage ofanother of said turbines, a reheat vapor generator, burner means forfiring said reheat vapor generator, a reheat element and saturated vaporgenerating surface disposed in said reheat generator, conduit means incommunication with the reheat vapor generator and each of said pluralityof vapor generators to pass vapor generated in the reheat vaporgenerator into admixture with vapor generated in each of said pluralityof vapor generators, control means for apportioning flow of vaporgenerated in said reheat generator between said plurality of vaporgenerators exhaust conduit means in communication with the high pressurestage of said one turbine and said reheat element, other exhaust conduitmeans in communication with the high pressure stage of said otherturbine and said reheat element, reheat conduit means in communicationwith said reheat element and the low pressure stage of said one turbine,other, reheat conduit means in communication with said reheat elementand the low pressure stage of said other turbine, and vapor conduitmeans for each of said plurality of vapor generators in communicationwith said saturated vapor generating surface and the superheater of eachof said plurality of vapor generators.

2. In combination, a plurality of vapor generators, a plurality offurnace chambers in each of said vapor generators, burner means disposedin each chamber, a superheater disposed in one of the chambers of eachvapor generator, a vapor generating surface in each of said plurality ofvapor generators, a plurality of turbines each having a high pressurestage and a low pressure stage, conduit means in communication with thesuperheater of one of said vapor generators and with the high pressurestage of one of said turbines, other conduit means in communication withthe superheater of another of said vapor generators and the highpressure stage of another of said turbines, a reheat vapor generator,burner means for firing said reheat vapor generator, a reheat elementand saturated vapor generating surface disposed in said reheatgenerator, conduit means in communication with the reheat vaporgenerator and each of said plurality of vapor generators to pass vaporgenerated in the reheat vapor generator into admixture with vaporgenerated m gamete each of said plurality of vapor generators, controlmeans for apportioning flow of vapor generated in said reheat generatorbetween said plurality of vapor generators exhause conduit means incommunication with the high pressure stage of said one turbine and withsaid reheat element, other exhaust conduit means in communication withthe high pressure stage of said other turbine and with said reheatelement, reheat conduit means in communication with said reheat elementand with the low pressure stage of said one turbine, other reheatconduit means in communication with said reheat element and with the lowpressure stage of said other turbine, and vapor conduit means for eachof said plurality of vapor generators in communication with saidsaturated vapor generating surface and the superheater of each of saidplurality of vapor generators.

3. In combination, a plurality of vapor generators each comprising asetting, a plurality of furnace chambers in said setting, independentlycontrolled .burner means for separately firing each chamber, a steam andwater drum and a water drum positioned in said setting, a bank oftubular members disposed in said setting and connected to said steam andwater drum and to said water drum, a superheater positioned in said bankof tubular members, a saturated steam conduit connected to said steamand water drum and to said superheater, a plurality of turbines eachhaving a high pressure stage and a low pressure stage, a superheatedsteam conduit connected to the superheater of one of said vaporgenerators and to the high pressure stage of one of said turbines,another superheated steam conduit connected to the superheater ofanother of said vapor generators and to the high pressure stage ofanother of said turbines, a reheat vapor generator, other burner meansfor firing said reheat vapor generator, a reheat element and saturatedvapor generating surface disposed in said reheat generator, a saturatedsteam conduit communicating at one end to said reheat generator toreceive saturated steam generated therein and at the other endcommunicating with each of said plurality of vapor generators to deliversaturated steam from the reheat generator into admixture with thesaturated steam generated in each of said plurality of vapor generators,control means in said saturated steam conduit for apportioning saturatedsteam generated in said reheat generator between each of the pluralityof vapor generators an exhaust steam conduit connected to the highpressure stage of said one turbine and to said reheat element, anotherexhaust steam conduit connected to the high pressure stage of said otherturbine and said reheat element, a reheated steam conduit connected tosaid reheat element and the low pressure stage of said one turbine,another reheated steam conduit connected to said reheat element and thelow pressure stage of said other turbine, and an auxiliary steam outletconduit connected to the saturated steam conduit of each of said vaporgenerators.

References Cited in the file of this patent UNITED STATES PATENTS1,635,410 Harter July 12, 1927 1,732,009 Gilbert Oct. 15, 1929 1,745,816Schwartz Feb. 4, 1930 1,751,238 Jacobus Mar. 18, 1930 1,931,948 ArmacostOct. 24, 1933 2,287,961 Barnes June 30, 1942 2,346,179 Meyer et al Apr.11, 1944 2,685,866 Yost Aug. 10,1954

